package jjn.acwing.java_basic;

import java.util.Scanner;

/**
 * @author Jjn
 * @since 2023/8/19 15:18
 */
public class Acwing714 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int x = scanner.nextInt();
        int y = scanner.nextInt();
        int min = Math.min(x, y);
        int max = Math.max(x, y);
        int sum = 0;
        for (int i = min + 1; i < max; i += 1) {
            if (i % 2 == 0) {
                continue;
            }
            sum += i;
        }
        System.out.println(sum);
    }
}
